Message-ID: <b699acc5-c704-1eb7-89b0-91f6efe5c6fd@st.com>
Date:   Fri, 2 Mar 2018 15:37:30 +0000
From:   Philippe CORNU <philippe.cornu@...com>
To:     Thierry Reding <thierry.reding@...il.com>
CC:     David Airlie <airlied@...ux.ie>, Rob Herring <robh+dt@...nel.org>,
        "Mark Rutland" <mark.rutland@....com>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Andrzej Hajda <a.hajda@...sung.com>,
        "Yannick FERTRE" <yannick.fertre@...com>,
        Benjamin Gaignard <benjamin.gaignard@...aro.org>,
        Vincent ABRIOU <vincent.abriou@...com>,
        Alexandre TORGUE <alexandre.torgue@...com>
Subject: Re: [PATCH v1 2/2] drm/panel: Add support for Raydium rm68200 panel
 driver

Hi Thierry,

A big thank you for your code review and comments.
It helped me to improve the driver and to send a v2.

Philippe :-)

On 02/28/2018 08:16 PM, Thierry Reding wrote:
> On Thu, Feb 08, 2018 at 03:30:26PM +0100, Philippe Cornu wrote:
>> This patch adds Raydium Semiconductor Corporation rm68200
>> 5.5" 720x1280 TFT LCD panel driver (MIPI-DSI video mode).
>>
>> Signed-off-by: Philippe Cornu <philippe.cornu@...com>
>> ---
>>   drivers/gpu/drm/panel/Kconfig                 |   8 +
>>   drivers/gpu/drm/panel/Makefile                |   1 +
>>   drivers/gpu/drm/panel/panel-raydium-rm68200.c | 464 ++++++++++++++++++++++++++
>>   3 files changed, 473 insertions(+)
>>   create mode 100755 drivers/gpu/drm/panel/panel-raydium-rm68200.c
>>
>> diff --git a/drivers/gpu/drm/panel/Kconfig b/drivers/gpu/drm/panel/Kconfig
>> index 988048ebcc22..08d99dd46765 100644
>> --- a/drivers/gpu/drm/panel/Kconfig
>> +++ b/drivers/gpu/drm/panel/Kconfig
>> @@ -108,6 +108,14 @@ config DRM_PANEL_RASPBERRYPI_TOUCHSCREEN
>>   	  Pi 7" Touchscreen.  To compile this driver as a module,
>>   	  choose M here.
>>   
>> +config DRM_PANEL_RAYDIUM_RM68200
>> +	tristate "Raydium rm68200 720x1280 dsi 2dl video mode panel"
> 
> What's 2dl? Either this is something already implied by the RM68200
> model or if there are multiple variants of the RM68200 you'll probably
> want to ensure that's reflected in the compatible string.
> 
>> +	depends on OF
>> +	depends on DRM_MIPI_DSI
>> +	help
>> +	  Say Y here if you want to enable support for Raydium rm68200
>> +	  720x1280 dsi 2dl video mode panel
>> +
>>   config DRM_PANEL_SAMSUNG_S6E3HA2
>>   	tristate "Samsung S6E3HA2 DSI video mode panel"
>>   	depends on OF
>> diff --git a/drivers/gpu/drm/panel/Makefile b/drivers/gpu/drm/panel/Makefile
>> index 3d2a88d0e965..f26efc11d746 100644
>> --- a/drivers/gpu/drm/panel/Makefile
>> +++ b/drivers/gpu/drm/panel/Makefile
>> @@ -9,6 +9,7 @@ obj-$(CONFIG_DRM_PANEL_LG_LG4573) += panel-lg-lg4573.o
>>   obj-$(CONFIG_DRM_PANEL_ORISETECH_OTM8009A) += panel-orisetech-otm8009a.o
>>   obj-$(CONFIG_DRM_PANEL_PANASONIC_VVX10F034N00) += panel-panasonic-vvx10f034n00.o
>>   obj-$(CONFIG_DRM_PANEL_RASPBERRYPI_TOUCHSCREEN) += panel-raspberrypi-touchscreen.o
>> +obj-$(CONFIG_DRM_PANEL_RAYDIUM_RM68200) += panel-raydium-rm68200.o
>>   obj-$(CONFIG_DRM_PANEL_SAMSUNG_LD9040) += panel-samsung-ld9040.o
>>   obj-$(CONFIG_DRM_PANEL_SAMSUNG_S6E3HA2) += panel-samsung-s6e3ha2.o
>>   obj-$(CONFIG_DRM_PANEL_SAMSUNG_S6E63J0X03) += panel-samsung-s6e63j0x03.o
>> diff --git a/drivers/gpu/drm/panel/panel-raydium-rm68200.c b/drivers/gpu/drm/panel/panel-raydium-rm68200.c
>> new file mode 100755
>> index 000000000000..f3e15873d05a
>> --- /dev/null
>> +++ b/drivers/gpu/drm/panel/panel-raydium-rm68200.c
>> @@ -0,0 +1,464 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Copyright (C) STMicroelectronics SA 2017
>> + *
>> + * Authors: Philippe Cornu <philippe.cornu@...com>
>> + *          Yannick Fertre <yannick.fertre@...com>
>> + */
>> +
>> +#include <drm/drmP.h>
>> +#include <drm/drm_mipi_dsi.h>
>> +#include <drm/drm_panel.h>
>> +#include <linux/backlight.h>
>> +#include <linux/gpio/consumer.h>
>> +#include <linux/regulator/consumer.h>
>> +#include <video/mipi_display.h>
>> +
>> +#define DRV_NAME "raydium_rm68200"
> 
> Not needed, see below.
> 
>> +
>> +/*** Manufacturer Command Set ***/
>> +#define MCS_CMD_MODE_SW	0xFE /* CMD Mode Switch */
>> +#define MCS_CMD1_UCS	0x00 /* User Command Set (UCS = CMD1) */
>> +#define MCS_CMD2_P0	0x01 /* Manufacture Command Set Page0 (CMD2 P0) */
>> +#define MCS_CMD2_P1	0x02 /* Manufacture Command Set Page1 (CMD2 P1) */
>> +#define MCS_CMD2_P2	0x03 /* Manufacture Command Set Page2 (CMD2 P2) */
>> +#define MCS_CMD2_P3	0x04 /* Manufacture Command Set Page3 (CMD2 P3) */
>> +
>> +/* CMD2 P0 commands (Display Options and Power) */
>> +#define MCS_STBCTR	0x12 /* TE1 Output Setting Zig-Zag Connection */
>> +#define MCS_SGOPCTR	0x16 /* Source Bias Current */
>> +#define MCS_SDCTR	0x1A /* Source Output Delay Time */
>> +#define MCS_INVCTR	0x1B /* Inversion Type */
>> +#define MCS_EXT_PWR_IC	0x24 /* External PWR IC Control */
>> +#define MCS_SETAVDD	0x27 /* PFM Control for AVDD Output */
>> +#define MCS_SETAVEE	0x29 /* PFM Control for AVEE Output */
>> +#define MCS_BT2CTR	0x2B /* DDVDL Charge Pump Control */
>> +#define MCS_BT3CTR	0x2F /* VGH Charge Pump Control */
>> +#define MCS_BT4CTR	0x34 /* VGL Charge Pump Control */
>> +#define MCS_VCMCTR	0x46 /* VCOM Output Level Control */
>> +#define MCS_SETVGN	0x52 /* VG M/S N Control */
>> +#define MCS_SETVGP	0x54 /* VG M/S P Control */
>> +#define MCS_SW_CTRL	0x5F /* Interface Control for PFM and MIPI */
>> +
>> +/* CMD2 P2 commands (GOA Timing Control) - no description in datasheet */
>> +#define GOA_VSTV1	0x00
>> +#define GOA_VSTV2	0x07
>> +#define GOA_VCLK1	0x0E
>> +#define GOA_VCLK2	0x17
>> +#define GOA_VCLK_OPT1	0x20
>> +#define GOA_BICLK1	0x2A
>> +#define GOA_BICLK2	0x37
>> +#define GOA_BICLK3	0x44
>> +#define GOA_BICLK4	0x4F
>> +#define GOA_BICLK_OPT1	0x5B
>> +#define GOA_BICLK_OPT2	0x60
>> +#define MCS_GOA_GPO1	0x6D
>> +#define MCS_GOA_GPO2	0x71
>> +#define MCS_GOA_EQ	0x74
>> +#define MCS_GOA_CLK_GALLON 0x7C
>> +#define MCS_GOA_FS_SEL0	0x7E
>> +#define MCS_GOA_FS_SEL1	0x87
>> +#define MCS_GOA_FS_SEL2	0x91
>> +#define MCS_GOA_FS_SEL3	0x9B
>> +#define MCS_GOA_BS_SEL0	0xAC
>> +#define MCS_GOA_BS_SEL1	0xB5
>> +#define MCS_GOA_BS_SEL2	0xBF
>> +#define MCS_GOA_BS_SEL3	0xC9
>> +#define MCS_GOA_BS_SEL4	0xD3
>> +
>> +/* CMD2 P3 commands (Gamma) */
>> +#define MCS_GAMMA_VP	0x60 /* Gamma VP1~VP16 */
>> +#define MCS_GAMMA_VN	0x70 /* Gamma VN1~VN16 */
>> +
>> +struct rm68200 {
>> +	struct device *dev;
>> +	struct drm_panel panel;
>> +	struct gpio_desc *reset_gpio;
>> +	struct regulator *supply;
>> +	struct backlight_device *bl_dev;
>> +	bool prepared;
>> +	bool enabled;
>> +};
>> +
>> +static const struct drm_display_mode default_mode = {
>> +	.clock = 52582,
>> +	.hdisplay = 720,
>> +	.hsync_start = 720 + 38,
>> +	.hsync_end = 720 + 38 + 8,
>> +	.htotal = 720 + 38 + 8 + 38,
>> +	.vdisplay = 1280,
>> +	.vsync_start = 1280 + 12,
>> +	.vsync_end = 1280 + 12 + 4,
>> +	.vtotal = 1280 + 12 + 4 + 12,
>> +	.vrefresh = 50,
>> +	.flags = 0,
>> +	.width_mm = 68,
>> +	.height_mm = 122,
>> +};
>> +
>> +static inline struct rm68200 *panel_to_rm68200(struct drm_panel *panel)
>> +{
>> +	return container_of(panel, struct rm68200, panel);
>> +}
>> +
>> +static void rm68200_dcs_write_buf(struct rm68200 *ctx, const void *data,
>> +				  size_t len)
>> +{
>> +	struct mipi_dsi_device *dsi = to_mipi_dsi_device(ctx->dev);
>> +
>> +	if (mipi_dsi_dcs_write_buffer(dsi, data, len) < 0)
>> +		DRM_WARN("mipi dsi dcs write buffer failed\n");
>> +}
>> +
>> +static void rm68200_dcs_write_cmd(struct rm68200 *ctx, u8 cmd, u8 value)
>> +{
>> +	struct mipi_dsi_device *dsi = to_mipi_dsi_device(ctx->dev);
>> +
>> +	if (mipi_dsi_dcs_write(dsi, cmd, &value, 1) < 0)
>> +		DRM_WARN("mipi dsi dcs write failed\n");
>> +}
> 
> I question the usefulness of your error reporting here. You're not
> giving the user any meaningful feedback. Also, you'll be warning about
> every single failure. It's likely that if one of the writes fails, then
> subsequent writes will also fail, which means that you'll give the user
> a flood of DRM_WARN() with exactly the same text.
> 
>> +/*
>> + * This panel is not able to auto-increment all cmd addresses so for some of
>> + * them, we need to send them one by one...
>> + */
>> +#define dcs_write_cmd_seq(ctx, cmd, seq...)			\
>> +({								\
>> +	static const u8 d[] = { seq };				\
>> +	static int i;						\
>> +	for (i = 0; i < ARRAY_SIZE(d) ; i++)			\
>> +		rm68200_dcs_write_cmd(ctx, cmd + i, d[i]);	\
>> +})
>> +
>> +static void rm68200_init_sequence(struct rm68200 *ctx)
>> +{
>> +	/* Enter CMD2 with page 0 */
>> +	dcs_write_seq(ctx, MCS_CMD_MODE_SW, MCS_CMD2_P0);
>> +	dcs_write_cmd_seq(ctx, MCS_EXT_PWR_IC, 0xC0, 0x53, 0x00);
>> +	dcs_write_seq(ctx, MCS_BT2CTR, 0xE5);
>> +	dcs_write_seq(ctx, MCS_SETAVDD, 0x0A);
>> +	dcs_write_seq(ctx, MCS_SETAVEE, 0x0A);
>> +	dcs_write_seq(ctx, MCS_SGOPCTR, 0x52);
>> +	dcs_write_seq(ctx, MCS_BT3CTR, 0x53);
>> +	dcs_write_seq(ctx, MCS_BT4CTR, 0x5A);
>> +	dcs_write_seq(ctx, MCS_INVCTR, 0x00);
>> +	dcs_write_seq(ctx, MCS_STBCTR, 0x0A);
>> +	dcs_write_seq(ctx, MCS_SDCTR, 0x06);
>> +	dcs_write_seq(ctx, MCS_VCMCTR, 0x56);
>> +	dcs_write_seq(ctx, MCS_SETVGN, 0xA0, 0x00);
>> +	dcs_write_seq(ctx, MCS_SETVGP, 0xA0, 0x00);
>> +	dcs_write_seq(ctx, MCS_SW_CTRL, 0x11); /* 2 data lanes, see doc */
>> +
>> +	dcs_write_seq(ctx, MCS_CMD_MODE_SW, MCS_CMD2_P2);
>> +	dcs_write_seq(ctx, GOA_VSTV1, 0x05);
>> +	dcs_write_seq(ctx, 0x02, 0x0B);
>> +	dcs_write_seq(ctx, 0x03, 0x0F);
>> +	dcs_write_seq(ctx, 0x04, 0x7D, 0x00, 0x50);
>> +	dcs_write_cmd_seq(ctx, GOA_VSTV2, 0x05, 0x16, 0x0D, 0x11, 0x7D, 0x00,
>> +			  0x50);
>> +	dcs_write_cmd_seq(ctx, GOA_VCLK1, 0x07, 0x08, 0x01, 0x02, 0x00, 0x7D,
>> +			  0x00, 0x85, 0x08);
>> +	dcs_write_cmd_seq(ctx, GOA_VCLK2, 0x03, 0x04, 0x05, 0x06, 0x00, 0x7D,
>> +			  0x00, 0x85, 0x08);
>> +	dcs_write_seq(ctx, GOA_VCLK_OPT1, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
>> +		      0x00, 0x00, 0x00, 0x00);
>> +	dcs_write_cmd_seq(ctx, GOA_BICLK1, 0x07, 0x08);
>> +	dcs_write_seq(ctx, 0x2D, 0x01);
>> +	dcs_write_seq(ctx, 0x2F, 0x02, 0x00, 0x40, 0x05, 0x08, 0x54, 0x7D,
>> +		      0x00);
>> +	dcs_write_cmd_seq(ctx, GOA_BICLK2, 0x03, 0x04, 0x05, 0x06, 0x00);
>> +	dcs_write_seq(ctx, 0x3D, 0x40);
>> +	dcs_write_seq(ctx, 0x3F, 0x05, 0x08, 0x54, 0x7D, 0x00);
>> +	dcs_write_seq(ctx, GOA_BICLK3, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
>> +		      0x00, 0x00, 0x00, 0x00, 0x00);
>> +	dcs_write_seq(ctx, GOA_BICLK4, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
>> +		      0x00, 0x00);
>> +	dcs_write_seq(ctx, 0x58, 0x00, 0x00, 0x00);
>> +	dcs_write_seq(ctx, GOA_BICLK_OPT1, 0x00, 0x00, 0x00, 0x00, 0x00);
>> +	dcs_write_seq(ctx, GOA_BICLK_OPT2, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
>> +		      0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00);
>> +	dcs_write_seq(ctx, MCS_GOA_GPO1, 0x00, 0x00, 0x00, 0x00);
>> +	dcs_write_seq(ctx, MCS_GOA_GPO2, 0x00, 0x20, 0x00);
>> +	dcs_write_seq(ctx, MCS_GOA_EQ, 0x08, 0x08, 0x08, 0x08, 0x08, 0x08,
>> +		      0x00, 0x00);
>> +	dcs_write_seq(ctx, MCS_GOA_CLK_GALLON, 0x00, 0x00);
>> +	dcs_write_cmd_seq(ctx, MCS_GOA_FS_SEL0, 0xBF, 0x02, 0x06, 0x14, 0x10,
>> +			  0x16, 0x12, 0x08, 0x3F);
>> +	dcs_write_cmd_seq(ctx, MCS_GOA_FS_SEL1, 0x3F, 0x3F, 0x3F, 0x3F, 0x0C,
>> +			  0x0A, 0x0E, 0x3F, 0x3F, 0x00);
>> +	dcs_write_cmd_seq(ctx, MCS_GOA_FS_SEL2, 0x04, 0x3F, 0x3F, 0x3F, 0x3F,
>> +			  0x05, 0x01, 0x3F, 0x3F, 0x0F);
>> +	dcs_write_cmd_seq(ctx, MCS_GOA_FS_SEL3, 0x0B, 0x0D, 0x3F, 0x3F, 0x3F,
>> +			  0x3F);
>> +	dcs_write_cmd_seq(ctx, 0xA2, 0x3F, 0x09, 0x13, 0x17, 0x11, 0x15);
>> +	dcs_write_cmd_seq(ctx, 0xA9, 0x07, 0x03, 0x3F);
>> +	dcs_write_cmd_seq(ctx, MCS_GOA_BS_SEL0, 0x3F, 0x05, 0x01, 0x17, 0x13,
>> +			  0x15, 0x11, 0x0F, 0x3F);
>> +	dcs_write_cmd_seq(ctx, MCS_GOA_BS_SEL1, 0x3F, 0x3F, 0x3F, 0x3F, 0x0B,
>> +			  0x0D, 0x09, 0x3F, 0x3F, 0x07);
>> +	dcs_write_cmd_seq(ctx, MCS_GOA_BS_SEL2, 0x03, 0x3F, 0x3F, 0x3F, 0x3F,
>> +			  0x02, 0x06, 0x3F, 0x3F, 0x08);
>> +	dcs_write_cmd_seq(ctx, MCS_GOA_BS_SEL3, 0x0C, 0x0A, 0x3F, 0x3F, 0x3F,
>> +			  0x3F, 0x3F, 0x0E, 0x10, 0x14);
>> +	dcs_write_cmd_seq(ctx, MCS_GOA_BS_SEL4, 0x12, 0x16, 0x00, 0x04, 0x3F);
>> +	dcs_write_seq(ctx, 0xDC, 0x02);
>> +	dcs_write_seq(ctx, 0xDE, 0x12);
>> +
>> +	dcs_write_seq(ctx, MCS_CMD_MODE_SW, 0x0E); /* No documentation */
>> +	dcs_write_seq(ctx, 0x01, 0x75);
>> +
>> +	dcs_write_seq(ctx, MCS_CMD_MODE_SW, MCS_CMD2_P3);
>> +	dcs_write_cmd_seq(ctx, MCS_GAMMA_VP, 0x00, 0x0C, 0x12, 0x0E, 0x06,
>> +			  0x12, 0x0E, 0x0B, 0x15, 0x0B, 0x10, 0x07, 0x0F,
>> +			  0x12, 0x0C, 0x00);
>> +	dcs_write_cmd_seq(ctx, MCS_GAMMA_VN, 0x00, 0x0C, 0x12, 0x0E, 0x06,
>> +			  0x12, 0x0E, 0x0B, 0x15, 0x0B, 0x10, 0x07, 0x0F,
>> +			  0x12, 0x0C, 0x00);
>> +
>> +	/* Exit CMD2 */
>> +	dcs_write_seq(ctx, MCS_CMD_MODE_SW, MCS_CMD1_UCS);
>> +}
>> +
>> +static int rm68200_disable(struct drm_panel *panel)
>> +{
>> +	struct rm68200 *ctx = panel_to_rm68200(panel);
>> +
>> +	if (!ctx->enabled)
>> +		return 0;
>> +
>> +	if (ctx->bl_dev) {
>> +		ctx->bl_dev->props.power = FB_BLANK_POWERDOWN;
>> +		ctx->bl_dev->props.state |= BL_CORE_FBBLANK;
>> +		backlight_update_status(ctx->bl_dev);
>> +	}
> 
> This should use the new backlight_disable() function.
> 
>> +
>> +	ctx->enabled = false;
>> +
>> +	return 0;
>> +}
>> +
>> +static int rm68200_unprepare(struct drm_panel *panel)
>> +{
>> +	struct rm68200 *ctx = panel_to_rm68200(panel);
>> +	struct mipi_dsi_device *dsi = to_mipi_dsi_device(ctx->dev);
>> +	int ret;
>> +
>> +	if (!ctx->prepared)
>> +		return 0;
>> +
>> +	ret = mipi_dsi_dcs_set_display_off(dsi);
>> +	if (ret)
>> +		DRM_WARN("failed to set display off: %d\n", ret);
>> +
>> +	ret = mipi_dsi_dcs_enter_sleep_mode(dsi);
>> +	if (ret)
>> +		DRM_WARN("failed to enter sleep mode: %d\n", ret);
>> +
>> +	msleep(120);
>> +
>> +	if (ctx->reset_gpio) {
>> +		gpiod_set_value_cansleep(ctx->reset_gpio, 1);
>> +		msleep(20);
>> +	}
>> +
>> +	regulator_disable(ctx->supply);
>> +
>> +	ctx->prepared = false;
>> +
>> +	return 0;
>> +}
>> +
>> +static int rm68200_prepare(struct drm_panel *panel)
>> +{
>> +	struct rm68200 *ctx = panel_to_rm68200(panel);
>> +	struct mipi_dsi_device *dsi = to_mipi_dsi_device(ctx->dev);
>> +	int ret;
>> +
>> +	if (ctx->prepared)
>> +		return 0;
>> +
>> +	ret = regulator_enable(ctx->supply);
>> +	if (ret < 0) {
>> +		DRM_ERROR("failed to enable supply: %d\n", ret);
>> +		return ret;
>> +	}
>> +
>> +	if (ctx->reset_gpio) {
>> +		gpiod_set_value_cansleep(ctx->reset_gpio, 0);
> 
> Why do you need this? If the panel is already in reset, shouldn't the
> below still work? Why take it out of reset only to reset it immediately
> afterwards again?
> 
>> +		gpiod_set_value_cansleep(ctx->reset_gpio, 1);
>> +		msleep(20);
>> +		gpiod_set_value_cansleep(ctx->reset_gpio, 0);
>> +		msleep(100);
>> +	}
>> +
>> +	rm68200_init_sequence(ctx);
>> +
>> +	ret = mipi_dsi_dcs_exit_sleep_mode(dsi);
>> +	if (ret)
>> +		return ret;
>> +
>> +	msleep(125);
>> +
>> +	ret = mipi_dsi_dcs_set_display_on(dsi);
>> +	if (ret)
>> +		return ret;
>> +
>> +	msleep(20);
>> +
>> +	ctx->prepared = true;
>> +
>> +	return 0;
>> +}
>> +
>> +static int rm68200_enable(struct drm_panel *panel)
>> +{
>> +	struct rm68200 *ctx = panel_to_rm68200(panel);
>> +
>> +	if (ctx->enabled)
>> +		return 0;
>> +
>> +	if (ctx->bl_dev) {
>> +		ctx->bl_dev->props.state &= ~BL_CORE_FBBLANK;
>> +		ctx->bl_dev->props.power = FB_BLANK_UNBLANK;
>> +		backlight_update_status(ctx->bl_dev);
>> +	}
> 
> backlight_enable(), please.
> 
>> +
>> +	ctx->enabled = true;
>> +
>> +	return 0;
>> +}
>> +
>> +static int rm68200_get_modes(struct drm_panel *panel)
>> +{
>> +	struct drm_display_mode *mode;
>> +
>> +	mode = drm_mode_duplicate(panel->drm, &default_mode);
>> +	if (!mode) {
>> +		DRM_ERROR("failed to add mode %ux%ux@%u\n",
>> +			  default_mode.hdisplay, default_mode.vdisplay,
>> +			  default_mode.vrefresh);
>> +		return -ENOMEM;
>> +	}
>> +
>> +	drm_mode_set_name(mode);
>> +
>> +	mode->type = DRM_MODE_TYPE_DRIVER | DRM_MODE_TYPE_PREFERRED;
>> +	drm_mode_probed_add(panel->connector, mode);
>> +
>> +	panel->connector->display_info.width_mm = mode->width_mm;
>> +	panel->connector->display_info.height_mm = mode->height_mm;
>> +
>> +	return 1;
>> +}
>> +
>> +static const struct drm_panel_funcs rm68200_drm_funcs = {
>> +	.disable   = rm68200_disable,
>> +	.unprepare = rm68200_unprepare,
>> +	.prepare   = rm68200_prepare,
>> +	.enable    = rm68200_enable,
>> +	.get_modes = rm68200_get_modes,
>> +};
>> +
>> +static int rm68200_probe(struct mipi_dsi_device *dsi)
>> +{
>> +	struct device *dev = &dsi->dev;
>> +	struct device_node *backlight;
>> +	struct rm68200 *ctx;
>> +	int ret;
>> +
>> +	ctx = devm_kzalloc(dev, sizeof(*ctx), GFP_KERNEL);
>> +	if (!ctx)
>> +		return -ENOMEM;
>> +
>> +	ctx->reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_LOW);
>> +	if (IS_ERR(ctx->reset_gpio)) {
>> +		dev_err(dev, "cannot get reset-gpio\n");
>> +		return PTR_ERR(ctx->reset_gpio);
>> +	}
>> +
>> +	ctx->supply = devm_regulator_get(dev, "power");
>> +	if (IS_ERR(ctx->supply)) {
>> +		dev_err(dev, "cannot get regulator\n");
>> +		return PTR_ERR(ctx->supply);
>> +	}
>> +
>> +	backlight = of_parse_phandle(dev->of_node, "backlight", 0);
>> +	if (backlight) {
>> +		ctx->bl_dev = of_find_backlight_by_node(backlight);
>> +		of_node_put(backlight);
>> +
>> +		if (!ctx->bl_dev)
>> +			return -EPROBE_DEFER;
>> +	}
> 
> devm_of_find_backlight()
> 
>> +
>> +	mipi_dsi_set_drvdata(dsi, ctx);
>> +
>> +	ctx->dev = dev;
>> +
>> +	dsi->lanes = 2;
>> +	dsi->format = MIPI_DSI_FMT_RGB888;
>> +	dsi->mode_flags = MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_BURST |
>> +			  MIPI_DSI_MODE_LPM;
>> +
>> +	drm_panel_init(&ctx->panel);
>> +	ctx->panel.dev = dev;
>> +	ctx->panel.funcs = &rm68200_drm_funcs;
>> +
>> +	drm_panel_add(&ctx->panel);
>> +
>> +	ret = mipi_dsi_attach(dsi);
>> +	if (ret < 0) {
>> +		dev_err(dev, "mipi_dsi_attach failed. Is host ready?\n");
>> +		drm_panel_remove(&ctx->panel);
>> +		if (ctx->bl_dev)
>> +			put_device(&ctx->bl_dev->dev);
>> +		return ret;
>> +	}
>> +
>> +	DRM_INFO(DRV_NAME "_panel %ux%u@%u %ubpp dsi %udl - ready\n",
>> +		 default_mode.hdisplay, default_mode.vdisplay,
>> +		 default_mode.vrefresh,
>> +		 mipi_dsi_pixel_format_to_bpp(dsi->format), dsi->lanes);
> 
> No need to brag about this being successful. That's what it's supposed
> to be. You should let the user know if things *don't* happen the way
> they're supposed to.
> 
>> +
>> +	return 0;
>> +}
>> +
>> +static int rm68200_remove(struct mipi_dsi_device *dsi)
>> +{
>> +	struct rm68200 *ctx = mipi_dsi_get_drvdata(dsi);
>> +
>> +	if (ctx->bl_dev)
>> +		put_device(&ctx->bl_dev->dev);
>> +
>> +	mipi_dsi_detach(dsi);
>> +	drm_panel_remove(&ctx->panel);
>> +
>> +	return 0;
>> +}
>> +
>> +static const struct of_device_id raydium_rm68200_of_match[] = {
>> +	{ .compatible = "raydium,rm68200" },
>> +	{ }
>> +};
>> +MODULE_DEVICE_TABLE(of, raydium_rm68200_of_match);
>> +
>> +static struct mipi_dsi_driver raydium_rm68200_driver = {
>> +	.probe  = rm68200_probe,
>> +	.remove = rm68200_remove,
>> +	.driver = {
>> +		.name = DRV_NAME "_panel",
> 
> This is the only occurrence so you can just drop DRV_NAME and put the
> name here.
> 
>> +		.of_match_table = raydium_rm68200_of_match,
>> +	},
>> +};
>> +module_mipi_dsi_driver(raydium_rm68200_driver);
>> +
>> +MODULE_AUTHOR("Philippe Cornu <philippe.cornu@...com>");
>> +MODULE_AUTHOR("Yannick Fertre <yannick.fertre@...com>");
>> +MODULE_DESCRIPTION("DRM Driver for Raydium RM68200 MIPI DSI panel");
> 
> You use RM68200 here but in other places you use rm68200. Please be
> consistent. It seems like RM68200 is the "official" spelling, so stick
> to that in prose.
> 
> Thierry
> 

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